initial commit

2020-05-19 18:20:18 +02:00 · 2020-05-19 18:20:18 +02:00 · 429a176559
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--- a/.gitignore
+++ b/.gitignore
@ -0,0 +1,3 @@
+/public
+/.idea/
+/blog.iml
--- a/config.toml
+++ b/config.toml
@ -0,0 +1,56 @@
+title = "Harald Hoyer"
+description = "Triple Faults for Debug"
+
+# The URL the site will be built for
+base_url = "https://harald.hoyer.xyz"
+
+# Whether to automatically compile all Sass files in the sass directory
+compile_sass = true
+
+# Whether to do syntax highlighting
+# Theme can be customised by setting the `highlight_theme` variable to a theme supported by Zola
+highlight_code = true
+
+# Whether to build a search index to be used later on by a JavaScript library
+build_search_index = true
+
+theme = "zola-clean-blog"
+
+taxonomies = [
+    {name = "categories", rss = true, paginate_by=5},
+    {name = "tags", rss = true, paginate_by=5},
+]
+
+generate_rss = true
+
+#highlight_theme = "dracula"
+#highlight_theme = "inspired-github"
+highlight_theme = "ir-white"
+#highlight_theme = "material-light"
+
+extra_syntaxes = [
+    "syntaxes",
+    "syntaxes/Sublime-varlink",
+    "syntaxes/Sublime-console",
+]
+
+[extra]
+# Put all your custom variables here
+
+author = "Harald Hoyer"
+
+clean_blog_menu = [
+    {url = "$BASE_URL", name = "Home"},
+    {url = "https://photo-harald.hoyer.xyz/", name = "Photos"},
+    {url = "$BASE_URL/impressum", name = "Impressum"},
+]
+
+clean_blog_social = [
+    {url = "https://hoyer.xyz/profile/harald", icon="fab fa-mastodon"},
+    {url = "https://github.com/haraldh", icon="fab fa-github"},
+    {url = "https://keybase.io/haraldhoyer/", icon="fab fa-keybase"},
+    {url = "https://twitter.com/haraldhoyer", icon="fab fa-twitter"},
+    {url = "$BASE_URL/rss.xml", icon="fas fa-rss"}
+]
+
+
--- a/content/2013/11/04/_index.md
+++ b/content/2013/11/04/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2013/11/04/dracut-kernel-command-line.md
+++ b/content/2013/11/04/dracut-kernel-command-line.md
@ -0,0 +1,18 @@
+++
+title = "dracut - kernel command line"
+date = 2013-11-04T18:36:27+00:00
+++
+To quickly find out, what dracut wants as the kernel command for your current disk setup,
+fire up:
+```console
+# dracut --print-cmdline
+``` 
+<!-- more -->
+
+It will output something like: 
+```bash
+root=UUID=8b8b6f91-95c7-4da2-831b-171e12179081
+rootflags=rw,relatime,discard,data=ordered
+rootfstype=ext4
+```
+This works for version 032 and newer.
--- a/content/2013/11/07/_index.md
+++ b/content/2013/11/07/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2013/11/07/redirecting-apache-access_log-and-error_log-to-the-systemd-journal.md
+++ b/content/2013/11/07/redirecting-apache-access_log-and-error_log-to-the-systemd-journal.md
@ -0,0 +1,17 @@
+++
+title = "Redirecting apache access_log and error_log to the systemd journal"
+date = 2013-11-07T10:03:38+00:00
+++
+To redirect all apache messages to syslog, which will then appear in the systemd 
+journal modify your httpd.conf: 
+
+<!-- more -->
+
+```properties
+CustomLog "|/bin/logger -t access_log -p user.info" "%v %h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\""``
+ErrorLog syslog:user
+```
+
+Of course it would be much nicer, if apache actually could use the journal directly. 
+
+\[Edit\]: Apparently with apache 2.5, there will be a [mod\_journald](http://httpd.apache.org/docs/trunk/mod/mod_journald.html) :\-)
--- a/content/2013/11/13/_index.md
+++ b/content/2013/11/13/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2013/11/13/fedora-boot-optimization.md
+++ b/content/2013/11/13/fedora-boot-optimization.md
@ -0,0 +1,152 @@
+++
+title = "Fedora Boot Optimization"
+date = 2013-11-13T10:12:04+00:00
+++
+This article shows how to reduce boot time for Fedora 17, but the recipe can also be applied to 18, 19 and 20.
+
+The target is to get a fast booting system with NetworkManager running and gdm displaying the login
+screen as fast as possible.
+
+<!-- more -->
+
+The system I use here is a Lenovo T420s (2x2x Intel(R) Core(TM) i5-2540M CPU @ 2.60GHz) 
+with an INTEL SSDSA2BW160G3L harddrive. 
+
+First we choose a manual disk layout and use primary partitions and format them with ext4. 
+In my case this results in:
+```sda1 ext4 /boot
+sda2 swap
+sda3 ext4
+```
+
+After the first boot, setup of the user, etc. and 2 reboots (always reboot 2 times, 
+before taking the measurement, because readahead needs to adapt to the changed boot process). 
+First we update everything.
+```console
+$ sudo yum update
+```
+After the reboots, I get:
+```console
+$ systemd-analyze
+Startup finished in 1413ms (kernel) + 2911ms (initramfs) + 10593ms (userspace) = 14918ms
+```
+
+Because I don't use any LVM, RAID or encrypted devices, I can safely turn off all nearly all 
+`fedora-\*storage\*` services. To turn off these services, we use the `systemctl mask` command.
+A bonus with that mechanism is, that no rpm %post script turns them on automatically.
+```console
+$ cd /lib/systemd/system
+$ for i in fedora*storage* lvm2-monitor.* mdmonitor*.*; \
+ do sudo systemctl mask $i; \
+ done
+```
+On Fedora 17, it seems there are still some SysV initscripts left, so we turn them off:
+```console
+$ for i in livesys livesys-late spice-vdagentd;\
+ do sudo chkconfig $i off;\
+ done
+```
+
+Seems like we saved half of the time in userspace:
+```console
+$ systemd-analyze
+Startup finished in 1640ms (kernel) + 6556ms (userspace) = 8197ms
+```
+
+From now on, you really have to know what you are doing and how to revert your actions. 
+To compare Fedora with e.g. Ubuntu, I will now turn off all services except NetworkManager. 
+The result will be a Linux system without mail, firewall, printing, the abrt tools, avahi, 
+some mountpoints, rsyslog, irqbalance, and selinux security.
+```console
+$ cd /lib/systemd/system
+$ for i in abrt*.service auditd.service avahi-daemon.* \
+ bluetooth.* dev-hugepages.mount dev-mqueue.mount \
+ fedora-configure.service fedora-loadmodules.service \
+ fedora-readonly.service ip6tables.service \
+ iptables.service irqbalance.service mcelog.service \
+ rsyslog.service sendmail.service sm-client.service \
+ sys-kernel-config.mount sys-kernel-debug.mount; do \
+ sudo systemctl mask "$i"; \
+ done
+```
+
+To disable selinux (only for measurements!), edit `/etc/selinux/config` and add `selinux=0`
+to the kernel command line.
+
+My `/etc/grub2.cfg` now looks like this:
+```
+linux /vmlinuz-3.3.7-1.fc17.x86_64 root=/dev/sda3 rootfstype=ext4 libahci.ignore_sss=1 raid=noautodetect selinux=0
+initrd /initramfs-3.3.7-1.fc17.x86_64.img
+```
+
+Now we are really fast!
+```console
+$ systemd-analyze
+Startup finished in 1329ms (kernel) + 1596ms (userspace) = 2926ms
+```
+
+I also like the idea of automounting (systemd's automount feature was an idea of mine :-). 
+So I turn /boot in a "mount on demand" mountpoint. Also having /tmp as a tmpfs is one way to reduce 
+disk activity (useful for e.g. a slow flash disk). My resulting /etc/fstab looks like this:
+```
+/dev/sda3 / ext4 defaults 1 1
+/dev/sda1 /boot ext4 noauto,comment=systemd.automount 1 2
+/dev/sda2 swap swap defaults 0 0
+tmpfs /tmp tmpfs defaults 0 0
+```
+
+This only saved a little bit of time, but still:
+```console
+$ systemd-analyze
+Startup finished in 1342ms (kernel) + 1426ms (userspace) = 2769ms
+```
+
+Because NetworkManager is started also by the graphical login target, 
+I can remove it from the multi-user target and it will be started in parallel to the gdm login screen.
+```console
+$ sudo rm /etc/systemd/system/multi-user.target.wants/NetworkManager.service
+```
+
+This will shave of a few milliseconds:
+```console
+$ systemd-analyze
+Startup finished in 1323ms (kernel) + 1279ms (userspace) = 2603ms
+```
+
+To see the difference readahead makes for the system, I turn it off temporarily and reboot
+```console
+$ cd /lib/systemd/system
+$ for i in *readahead*; do sudo systemctl mask $i;done
+```
+
+Which will give us:
+```console
+$ systemd-analyze
+Startup finished in 1336ms (kernel) + 1210ms (userspace) = 2547ms
+```
+
+This time is a little bit misleading. Although it seems faster, the real time until the login screen 
+is displayed is taking longer. So a fair comparison would involve a **stopwatch**.
+
+To turn off plymouth, because we want speed and not eye candy, I remove plymouth completely 
+and regenerate the initramfs to get rid of it.
+```console
+$ sudo yum remove 'plymouth*'
+$ sudo dracut -f
+``` 
+
+After a reboot we get the stunning result of:
+```console
+$ systemd-analyze
+Startup finished in 612ms (kernel) + 499ms (initramfs) + 1330ms (userspace) = 2443ms
+```
+
+The nice thing about `systemctl mask` is, that you can always unmask it via `systemctl unmask`
+and only enable those default services, which you really need.
+
+Now, **turn selinux back on**, edit `/etc/selinux/config` and remove `selinux=0` from the kernel command line.
+You really don't want to trade some seconds for security!
+
+Have fun and happy rebooting!
+
+And don't forget to reboot twice to let the readahead optimization kick in!
--- a/content/2013/11/13/linux-howto-get-the-number-of-cpus.md
+++ b/content/2013/11/13/linux-howto-get-the-number-of-cpus.md
@ -0,0 +1,17 @@
+++
+title = "Linux: HOWTO get the number of CPUs"
+date = 2013-11-13T12:13:04+00:00
+++
+```console
+$ getconf _NPROCESSORS_ONLN
+```
+returns the number of CPUs online.
+
+<!-- more -->
+
+Internally it is parsing
+`/sys/devices/system/cpu/online`, which can have the contents: `0-3,5,7-9`.
+
+Better let getconf [do all the counting for you](https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/getsysstats.c#l127).
+
+This is very useful, if you want to optimize the number of threads.
--- a/content/2013/11/_index.md
+++ b/content/2013/11/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2013/_index.md
+++ b/content/2013/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2014/01/14/_index.md
+++ b/content/2014/01/14/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2014/01/14/self-hosting-fedora-base.md
+++ b/content/2014/01/14/self-hosting-fedora-base.md
@ -0,0 +1,71 @@
+++
+title = "Self Hosting Fedora Base"
+date = 2014-01-14T16:15:52+00:00
+++
+If you want to bootstrap a distribution or want to rebuild it from the sources (SRPMS) to get the same 
+binaries (think CentOS), you have to build the build tools and rebuild them with the built build tools, 
+which have to be built with other build tools…
+
+My goal for a self-hosting Fedora Base is to reduce the number of packages to do such a rebuild.
+
+<!-- more -->
+
+The first step is to get the packages to build the most important component for a linux distribution - the kernel.
+
+To get those packages, Phil Knirsch wrote a small python script, which calls `repoquery`.
+I extended this script to output graphviz .dot formatted files. 
+
+The first run gives us [1806 packages](https://harald.fedorapeople.org/kernel-br-all.txt), with which you could build 
+the tools to build the tools to […] build the kernel, if you manage to break the dependency cycle, etc. 
+
+If you want to display this beast with e.g. "sfdp" and "gvmap" from the graphviz suite, this will give you a monster graph.
+
+[<img alt="Self-Hosting kernel build requirements" src="https://harald.fedorapeople.org/kernel-br-all.png" height="333" width="800" />](https://harald.fedorapeople.org/kernel-br-all.svg)
+Self-Hosting kernel build requirements
+
+This was generated with the [kernel-br-all.dot](https://harald.fedorapeople.org/kernel-br-all.dot) file and the command:
+```console
+$ START=7; cat kernel-br-all.dot | \
+ sfdp -Gstart=$START -Goverlap=prism | \
+ gvmap -e -d $START | \
+ neato -Gstart=$START -n2 -Ecolor=#44444455 -Tsvg \
+> kernel-br-all.svg
+```
+
+My next step was to identify the source of weird build requirements like `qt`, `kdelibs` or `wayland`. 
+So I build a list of packages, which might be removed from the build requirements, because they only build documentation
+or willingly add a build requirement to a graphical component like X, wayland or a GUI.
+
+After filtering those with [the python script](https://harald.fedorapeople.org/buildreq.py), the resulting graph was 
+mainly dominated by perl packages, so I just merged them in one "perl" node. The graph from this is almost readable. 
+
+[<img alt="Reduced Self-Hosting kernel build requirements" src="https://harald.fedorapeople.org/kernel-br-reduced.png" height="525" width="800" />](https://harald.fedorapeople.org/kernel-br-reduced.svg)
+Reduced Self-Hosting kernel build requirements
+
+`graphviz` comes with `tred`, which reduces the graph, so that at least one path leads from X to Y.
+With this reduction we get a nice graph generated from
+[kernel-br-reduced.dot](https://harald.fedorapeople.org/kernel-br-reduced.dot) by:
+
+```console
+$ START=7; tred kernel-br-reduced.dot | \
+ sfdp -Gstart=$START -Goverlap=prism | \
+ gvmap -e -d $START | \
+ neato -Gstart=$START -n2 -Ecolor=#44444455 -Tsvg \
+ > kernel-br-reduced-tred.svg
+```
+
+Now, most of the build requirements are missing, but one path, so you can at least find **one** package,
+which requires a specific package. All the red nodes in the graph are the build requirements, for which no
+build requirements were added. So the strategy should be to get rid of those, or make sure they don't pull in the #
+complete distribution. We might want to use the pre-built documentation shipped with the package or have a separate 
+documentation build phase with the same source. For other packages, we might have to split out the GUI components. 
+If you have other ideas, I am happy to get to know them.
+
+**Conclusion: 188 packages plus all the perl packages could form a basic buildroot to build itsself.
+To achieve this, we have to take care of those 56 red packages, that these are not used.** 
+
+The list of the 65 spec files with the build requirements to ifdef can be found here: 
+[http://harald.fedorapeople.org/bootstrap-not-needed-deps.txt](https://harald.fedorapeople.org/bootstrap-not-needed-deps.txt)
+ 
+[<img alt="" src="https://harald.fedorapeople.org/kernel-br-reduced-tred.svg" width="800" />](https://harald.fedorapeople.org/kernel-br-reduced-tred.svg)
+Reduced Build Requirements for the package kernel
--- a/content/2014/01/_index.md
+++ b/content/2014/01/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2014/_index.md
+++ b/content/2014/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2015/02/25/_index.md
+++ b/content/2015/02/25/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2015/02/25/single-uefi-executable-for-kernelinitrdcmdline.md
+++ b/content/2015/02/25/single-uefi-executable-for-kernelinitrdcmdline.md
@ -0,0 +1,41 @@
+++
+title = "Single UEFI executable for kernel+initrd+cmdline"
+date = 2015-02-25T15:55:16+00:00
+++
+
+Lately Kay Sievers and David Herrmann created a UEFI
+[loader stub](http://cgit.freedesktop.org/gummiboot/tree/src/efi/stub.c), which starts a linux kernel
+with an initrd and a kernel command line, which are COFF sections of the executable.
+This enables us to create single UEFI executable with a standard distribution kernel,
+a custom initrd and our own kernel command line attached.
+
+<!-- more -->
+
+Of course booting a linux kernel 
+directly from the UEFI has been possible before with the kernel EFI stub. But to add an initrd and 
+kernel command line, this had to be specified at kernel compile time.
+
+To demonstrate this feature 
+and have a useful product, I created a shell script, which creates a "rescue" image on Fedora with 
+the rescue kernel and rescue initrd. The kernel command line "rd.auto" instructs dracut to assemble 
+all devices, while waiting 20 seconds for device appearance "rd.retry=20" and drop to a final shell 
+because "root=/dev/failme" is specified (which does not exist of course). Now in this shell you can 
+fsck your devices, mount them and repair your system.
+
+The shell script can be downloaded and viewed on 
+[github](https://github.com/haraldh/mkrescue-uefi).
+
+To run the script, you will need to install gummiboot >= 46 and binutils. 
+```console
+# yum install gummiboot binutils
+```
+
+Run the script: 
+```console
+# bash mkrescue-uefi.sh BOOTX64.EFI
+```
+ 
+Copy `BOOTX64.EFI` to e.g. a USB stick to `EFI/BOOT/BOOTX64.EFI` in the FAT boot partition 
+and point your BIOS to boot from the USB stick. Voilà!
+
+A rescue USB stick with just one file! :-)
--- a/content/2015/02/_index.md
+++ b/content/2015/02/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2015/03/05/_index.md
+++ b/content/2015/03/05/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2015/03/05/libtool-getting-rid-of-180000-sed-forks.md
+++ b/content/2015/03/05/libtool-getting-rid-of-180000-sed-forks.md
@ -0,0 +1,79 @@
+++
+title = "libtool: getting rid of 180,000 sed forks"
+date = 2015-03-05T08:10:36+00:00
+++
+When compiling systemd on rawhide, we noticed a significant slowdown in compile time. 
+Investigating further, it turns out, that libtool forks an incredible amount of sed. 
+Running perf showed 30% of the "make all" was spent in bash. strace showed an execve of 
+sed with the same arguments 180,000 times!!!!! 
+
+<!-- more -->
+
+Looking in the code reveals the culprit:
+```bash
+_G_unquoted_arg=`printf '%s\n' "$1" |$SED "$sed_quote_subst"` ;;
+```
+and
+```bash
+qECHO=`$ECHO "$ECHO" | $SED "$sed_quote_subst"`
+```
+
+`sed_quote_subst` looks like this:
+```bash
+sed_quote_subst='s|\([`"$\\]\)|\\\1|g'
+``` 
+
+This substitution can be easily done in bash, without forking sed. So I came up with a patch for libtool:
+
+```diff
+--- libtool.orig	2015-03-04 15:44:39.632703654 +0100
+++ libtool.fixed	2015-03-04 17:16:42.495983610 +0100
+@@ -1607,7 +1607,15 @@
+     while test 0 -lt $#; do
+       case $1 in
+         *[\\\`\"\$]*)
+-	  _G_unquoted_arg=`printf '%s\n' "$1" |$SED "$sed_quote_subst"` ;;
+          if test set = "${BASH_VERSION+set}"; then
+            _G_unquoted_arg=${1//\\/\\\\}
+            _G_unquoted_arg=${_G_unquoted_arg//\"/\\\"}
+            _G_unquoted_arg=${_G_unquoted_arg//\$/\\\$}
+            _G_unquoted_arg=${_G_unquoted_arg//\`/\\\`}
+          else
+              _G_unquoted_arg=`printf '%s\n' "$1" |$SED "$sed_quote_subst"`
+          fi
+          ;;
+         *)
+           _G_unquoted_arg=$1 ;;
+       esac
+@@ -5756,7 +5764,11 @@
+   if test \"\$libtool_execute_magic\" != \"$magic\"; then
+     file=\"\$0\""
+
+-    qECHO=`$ECHO "$ECHO" | $SED "$sed_quote_subst"`
+    if test set = "${BASH_VERSION+set}"; then
+      qECHO=$(_G=$($ECHO "$ECHO");_G=${_G//\\/\\\\};_G=${_G//\"/\\\"};_G=${_G//\$/\\\$};_G=${_G//\`/\\\`};printf '%s\n' "$_G")
+    else
+      qECHO=`$ECHO "$ECHO" | $SED "$sed_quote_subst"`
+    fi
+     $ECHO "\
+```
+
+With that patch, I compared the runtime of a compile (with ccache on). Original libtool:
+```console
+$ time make -j4
+[…]
+real 5m23.880s
+user 11m39.731s
+sys 7m12.578s
+```
+Fixed libtool: 
+```console
+$ time make -j4
+[…]
+real 2m47.325s
+user 9m33.561s
+sys 0m57.522s
+```
+The old version spent half of the time creating a pipe, forking sed and parsing the 
+output. Someone with connections to the libtool maintainers, please point them to 
+this problem! Reported as [bug 20006](http://debbugs.gnu.org/cgi/bugreport.cgi?bug=20006).
--- a/content/2015/03/_index.md
+++ b/content/2015/03/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2015/10/13/_index.md
+++ b/content/2015/10/13/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2015/10/13/a-python-transaction-class.md
+++ b/content/2015/10/13/a-python-transaction-class.md
@ -0,0 +1,357 @@
+++
+title = "A Python Transaction Class"
+date = 2015-10-13T10:20:43+00:00
+++
+This is a repost of a blog post of 2008. Just for the reference :-)
+
+This class allows sub-classes to commit changes to an instance to a history, and rollback to previous states.
+
+<!-- more -->
+
+The final class with an extension for `__setstate__` and `__getstate__` can be found here:
+[transaction.py](/files/transaction.py)
+and [transaction_test.py](/files/transaction_test.py).
+
+Now to the story, that led to it: I had the need for a transaction class in python and browsing the python cookbook led me to a [small Transaction class](http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/551788).
+
+```python
+$ python
+Python 2.5.1 (r251:54863, Oct 30 2007, 13:45:26)
+[GCC 4.1.2 20070925 (Red Hat 4.1.2-33)] on linux2
+Type "help", "copyright", "credits" or "license" for more information.
+>>> class Transaction(object):
+...     def __init__(self):
+...         self.log = []
+...     def commit(self):
+...         self.log.append(self.__dict__.copy())
+...     def rollback(self):
+...         try:
+...             self.__dict__.update(self.log.pop(-1))
+...         except IndexError:
+...             pass
+...
+```
+
+ Ok, lets have some fun with it.
+
+```python
+>>> class A(Transaction):
+...     pass
+...
+>>> a = A()
+>>> a.test = True
+>>> a.commit()
+>>> a.test = False
+>>> a
+'self.__dict__ = {'test': False, 'log': [{'test': True, 'log': [...]}]}'
+>>> a.rollback()
+>>> a
+'self.__dict__ = {'test': True, 'log': []}'
+```
+
+ Nice. Let's see if we can commit and rollback several times.
+
+```python
+>>> a = A()
+>>> a.test = 1
+>>> a.commit()
+>>> a.test = 2
+>>> a.commit()
+>>> a.test = 3
+>>> a
+'self.__dict__ = {'test': 3, 'log': [{'test': 1, 'log': [...]}, {'test': 2, 'log': [...]}]}'
+>>> a.rollback()
+>>> a
+'self.__dict__ = {'test': 2, 'log': [{'test': 1, 'log': [...]}]}'
+>>> a.rollback()
+>>> a
+'self.__dict__ = {'test': 1, 'log': []}'
+```
+
+ Ok.. works :) Let's try some lists.
+
+```python
+>>> a = A()
+>>> a.test = [ 0, 1 ]
+>>> a.commit()
+>>> a.test.append(2)
+>>> a
+'self.__dict__ = {'test': [0, 1, 2], 'log': [{'test': [0, 1, 2], 'log': [...]}]}'
+>>> a.rollback()
+>>> a
+'self.__dict__ = {'test': [0, 1, 2], 'log': []}'
+```
+
+ Doh! Ok, someone mentioned that already in the comments. copy.deepcopy() is the key.
+
+```python
+>>> import copy
+>>>
+>>> class Transaction2(Transaction):
+...     def commit(self, **kwargs):
+...         self.log.append(copy.deepcopy(self.__dict__))
+...
+>>> class A(Transaction2):
+...     pass
+...
+>>> a = A()
+>>> a.test = [ 0, 1 ]
+>>> a.commit()
+>>> a.test.append(2)
+>>> a
+'self.__dict__ = {'test': [0, 1, 2], 'log': [{'test': [0, 1], 'log': []}]}'
+>>> a.rollback()
+>>> a
+'self.__dict__ = {'test': [0, 1], 'log': []}'
+
+```
+
+ Ah, works. Very good. Now another check:
+
+```python
+>>> a = A()
+>>> a.test = 1
+>>> a.commit()
+>>> a
+'self.__dict__ = {'test': 1, 'log': [{'test': 1, 'log': []}]}'
+>>> a.other = 2
+>>> a
+'self.__dict__ = {'test': 1, 'other': 2, 'log': [{'test': 1, 'log': []}]}'
+>>> a.rollback()
+>>> a
+'self.__dict__ = {'test': 1, 'other': 2, 'log': []}'
+>>> a.other
+2
+
+```
+
+ Oh, a leftover... seems like `self.__dict__` has to be cleared, before the update.
+
+```python
+>>> class Transaction3(Transaction2):
+...     def rollback(self, **kwargs):
+...         try:
+...             state = self.log.pop(-1)
+...             self.__dict__.clear()
+...             self.__dict__.update(state)
+...         except IndexError:
+...             pass
+...
+>>> class A(Transaction3):
+...     pass
+...
+>>> a = A()
+>>> a.test = 1
+>>> a.commit()
+>>> a
+'self.__dict__ = {'test': 1, 'log': [{'test': 1, 'log': []}]}'
+>>> a.other = 2
+>>> a
+'self.__dict__ = {'test': 1, 'other': 2, 'log': [{'test': 1, 'log': []}]}'
+>>> a.rollback()
+>>> a
+'self.__dict__ = {'test': 1, 'log': []}'
+>>> a.other
+Traceback (most recent call last):
+  File "", line 1, in
+AttributeError: 'A' object has no attribute 'other'
+>>>
+```
+
+ Ah, works. Very good. Ok, more tests...
+
+```python
+>>> b = a.ncls
+>>> a.ncls.test = True
+>>> a.commit()
+>>> a.ncls.test = False
+>>> a.rollback()
+>>> a
+'self.__dict__ = {'ncls': 'self.__dict__ = {'test': True, 'log': []}', 'log': []}'
+>>> b
+'self.__dict__ = {'test': False, 'log': []}'
+```
+
+ Oh, what if we work with "b", which stills holds the old value? Maybe we should commit() all our attributes also, traversing through them all? Ok, here is such a beast:
+
+```python
+>>> class TransactionNew1(object):           
+...     def _docommit(self):
+...         if "log" not in self.__dict__:
+...             self.__dict__["log"] = list()
+...             
+...         self.__dict__["log"].append(copy.deepcopy(self.__dict__))
+...     
+...     def _dorollback(self):
+...         if "log" not in self.__dict__:
+...             return
+...         try:
+...             state = self.__dict__["log"].pop(-1)
+...             self.__dict__.clear()
+...             self.__dict__.update(state)
+...         except IndexError:
+...             pass
+...     
+...     def commit(self, **kwargs):
+...         # commit ourselves, then our childs
+...         self._docommit()
+...         if kwargs.get("deep", True):
+...             for child in self.__dict__.values():
+...                 if isinstance(child, self.__class__):
+...                     child.commit()
+...                     
+...     def rollback(self, **kwargs):
+...         # rollback our childs, then ourselves
+...         if kwargs.get("deep", True):
+...             for child in self.__dict__.values():
+...                 if isinstance(child, self.__class__):
+...                     child.rollback()
+...         self._dorollback()
+...     
+...     def __repr__(self):
+...         return "'self.__dict__ = %s'" % self.__dict__
+...
+>>> class A(TransactionNew1):
+...     pass
+...
+>>> a = A()
+>>> a.ncls = A()
+>>> b = a.ncls
+>>> a.ncls.test = True
+>>> a.commit()
+>>> a.ncls.test = False
+>>> a.rollback()
+>>> a
+'self.__dict__ = {'ncls': 'self.__dict__ = {'test': True}', 'log': []}'
+>>> b
+'self.__dict__ = {'test': True, 'log': []}'
+
+```
+
+ Ok... looks good, but we lost the reference. id(b) != id(a.ncls) ... ( update: this is fixed in the final version ) Working with it revealed also:
+
+```python
+>>> a = A()
+>>> b = a
+>>> for i in xrange(3):
+...     b.n = A()
+...     b.t = "test"
+...     b = b.n
+...     a.commit()
+...
+>>> a
+'self.__dict__ = {'log': [{'n': 'self.__dict__ = {}', 'log': [], 't': 'test'}, {'n': 'self.__dict__ = {'log': [{'log': []}], 't': 'test', 'n': 'self.__dict__ = {}'}', 'log': [{'t': 'test', 'log': [], 'n': 'self.__dict__ = {}'}], 't': 'test'}, {'n': 'self.__dict__ = {'log': [{'log': []}, {'log': [{'log': []}], 't': 'test', 'n': 'self.__dict__ = {}'}], 't': 'test', 'n': 'self.__dict__ = {'log': [{'log': []}], 't': 'test', 'n': 'self.__dict__ = {}'}'}', 'log': [{'t': 'test', 'log': [], 'n': 'self.__dict__ = {}'}, {'t': 'test', 'log': [{'n': 'self.__dict__ = {}', 't': 'test', 'log': []}], 'n': 'self.__dict__ = {'t': 'test', 'log': [{'log': []}], 'n': 'self.__dict__ = {}'}'}], 't': 'test'}], 't': 'test', 'n': 'self.__dict__ = {'t': 'test', 'log': [{'log': []}, {'n': 'self.__dict__ = {}', 't': 'test', 'log': [{'log': []}]}, {'n': 'self.__dict__ = {'log': [{'log': []}], 't': 'test', 'n': 'self.__dict__ = {}'}', 't': 'test', 'log': [{'log': []}, {'log': [{'log': []}], 't': 'test', 'n': 'self.__dict__ = {}'}]}], 'n': 'self.__dict__ = {'t': 'test', 'log': [{'log': []}, {'n': 'self.__dict__ = {}', 't': 'test', 'log': [{'log': []}]}], 'n': 'self.__dict__ = {'log': [{'log': []}]}'}'}'}'
+>>> len(str(a))
+1192
+```
+
+ Hmm... seems strange.. Ah, self.log was also copied with copy.deepcopy(). So, we have multiple useless copies. Let's "pop()" the state from self.__dict__ before the deepcopy.
+
+```python
+>>> class TransactionNew2(TransactionNew1):
+...     def _docommit(self):
+...         if "log" in self.__dict__:
+...             oldstate = self.__dict__.pop("log")
+...         else:
+...             oldstate = None             
+...         state = copy.deepcopy(self.__dict__)
+...         if oldstate:
+...             state["log"] = oldstate
+...         self.__dict__["log"] = state
+...     def _dorollback(self):
+...         if "log" not in self.__dict__:
+...             return
+...         try:
+...             state = self.__dict__["log"]
+...             self.__dict__.clear()
+...             self.__dict__.update(state)
+...         except IndexError:
+...             pass
+...
+>>> class A(TransactionNew2):
+...     pass
+...
+>>>
+>>> a = A()
+>>> b = a
+>>> for i in xrange(3):
+...     b.n = A()
+...     b.t = "test"
+...     b = b.n
+...     a.commit()
+...
+>>> a
+'self.__dict__ = {'log': {'log': {'log': {'t': 'test', 'n': 'self.__dict__ = {}'}, 't': 'test', 'n': 'self.__dict__ = {'log': {}, 't': 'test', 'n': 'self.__dict__ = {}'}'}, 't': 'test', 'n': 'self.__dict__ = {'log': {'t': 'test', 'n': 'self.__dict__ = {}'}, 't': 'test', 'n': 'self.__dict__ = {'log': {}, 't': 'test', 'n': 'self.__dict__ = {}'}'}'}, 't': 'test', 'n': 'self.__dict__ = {'t': 'test', 'log': {'log': {'t': 'test', 'n': 'self.__dict__ = {}'}, 't': 'test', 'n': 'self.__dict__ = {'log': {}, 't': 'test', 'n': 'self.__dict__ = {}'}'}, 'n': 'self.__dict__ = {'t': 'test', 'log': {'t': 'test', 'n': 'self.__dict__ = {}'}, 'n': 'self.__dict__ = {'log': {}}'}'}'}'
+>>> len(str(a))
+671
+
+```
+
+ Ok, saved us a bit of state length. The final version has:
+
+```python
+>>> a
+'self.__dict__ = {'__l': {'__l': {'__l': {'t': 'test'}, 't': 'test'}, 't': 'test'}, 't': 'test', 'n': 'self.__dict__ = {'__l': {'__l': {'t': 'test'}, 't': 'test'}, 't': 'test', 'n': 'self.__dict__ = {'__l': {'t': 'test'}, 't': 'test', 'n': 'self.__dict__ = {'__l': {}}'}'}'}'
+>>> len(str(a))
+275
+
+```
+
+ Now another thing:
+
+```python
+>>> a = A()
+>>> a.n = a
+>>> a.commit()
+
+  File "/usr/lib64/python2.5/copy.py", line 162, in deepcopy
+    y = copier(x, memo)
+RuntimeError: maximum recursion depth exceeded
+```
+
+ ... Oh, oh! Recursion in commit()... Now we have to check, if we have been there.
+
+```python
+>>> class TransactionNew3(TransactionNew2):
+...     def _checksetseen(self, seen):
+...         if id(self) in seen:
+...             import sys
+...             sys.stderr.write("Recursion detected... \n")
+...             return True
+...         seen.add(id(self))
+...         return False
+...         
+...     def commit(self, **kwargs): # pylint: disable-msg=W0613
+...         seen = kwargs.get("_commit_seen", set())
+...         if self._checksetseen(seen):
+...             return
+...         # commit ourselves, then our childs
+...         self._docommit()
+...         if kwargs.get("deep", True):
+...             for child in self.__dict__.values():
+...                 if isinstance(child, self.__class__):
+...                     child.commit(_commit_seen = seen)
+...                     
+...     def rollback(self, **kwargs):
+...         seen = kwargs.get("_rollback_seen", set())
+...         if self._checksetseen(seen):
+...             return
+...         # rollback our childs, then ourselves
+...         if kwargs.get("deep", True):
+...             for child in self.__dict__.values():
+...                 if isinstance(child, self.__class__):
+...                     child.rollback(_rollback_seen = seen)
+...         self._dorollback()
+...
+>>>
+>>> class A(TransactionNew3):
+...     pass
+...
+>>> a = A()
+>>> a.n = a
+>>> a.commit()
+Recursion detected...
+>>>
+```
+
+The final class with an extension for `__setstate__` and `__getstate__` can be found here: [transaction.py](https://harald.hoyer.xyz/files/transaction.py) and [transaction_test.py](/files/transaction_test.py). Have fun with it :-)
--- a/content/2015/10/_index.md
+++ b/content/2015/10/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2015/_index.md
+++ b/content/2015/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2016/07/21/_index.md
+++ b/content/2016/07/21/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2016/07/21/gpg-smartcard-and-ssh.md
+++ b/content/2016/07/21/gpg-smartcard-and-ssh.md
@ -0,0 +1,87 @@
+++
+title = "GPG, Smartcard and ssh"
+date = 2016-07-21T14:35:14+00:00
+++
+
+This blog post shows how to tweak Fedora, if you want to use a smartcard with OpenPGP and use it also as a ssh key.
+It also serves me as a recipe for fresh installations. 
+<!-- more -->
+
+First, you have to disable gnome-keyring-ssh by:
+```console
+$ cp /etc/xdg/autostart/gnome-keyring-ssh.desktop \
+ $HOME/.config/autostart
+$ echo "Hidden=true" \
+ >> $HOME/.config/autostart/gnome-keyring-ssh.desktop
+```
+
+Because the pcscd daemon does not play nicely with scdaemon from gpg, we have two options.
+
+1. disable pcscd completely (recommended) by
+
+    ```console
+    $ sudo systemctl mask --now pcscd.socket
+    $ sudo systemctl mask --now pcscd.service
+    ```
+
+2. or a `$HOME/.gnupg/scdaemon.conf` with
+
+    ```properties
+    pcsc-driver /usr/lib64/libpcsclite.so.1
+    disable-ccid
+    ```
+
+In `$HOME/.gnupg/gpg.conf` `use-agent` should be enabled (should be the default anyway).
+
+`$HOME/.gnupg/gpg-agent.conf` should have: `enable-ssh-support`
+
+To point ssh to the gpg-agent my `.bashrc` contains the line:
+```bash
+unset SSH_AGENT_PID
+export SSH_AUTH_SOCK=$HOME/.gnupg/S.gpg-agent.ssh
+```
+
+on newer systems, this can be
+```bash
+export SSH_AUTH_SOCK=/run/user/$UID/gnupg/S.gpg-agent.ssh
+```
+
+Relogin or reboot to get rid of gnome-keyring-ssh. 
+
+Now `gpg2 --card-status` and `ssh-add -L` should work as expected:
+```console
+$ gpg2 --card-status
+Reader ...........: 1050:0116:X:0
+Application ID ...: D2760001240102000006045502760000
+Version ..........: 2.0
+Manufacturer .....: Yubico
+Serial number ....: XXXX
+Name of cardholder: Harald Hoyer
+Language prefs ...: de
+Sex ..............: male
+URL of public key : hkp://pool.sks-keyservers.net
+Login data .......: [not set]
+Signature PIN ....: forced
+Key attributes ...: rsa2048 rsa2048 rsa2048
+Max. PIN lengths .: 127 127 127
+PIN retry counter : 3 3 3
+Signature counter : 23
+Signature key ....: 8745 5B0B B9F9 CDC3 619D C4FE 7BDB F42F AF81 54A2 created ....: 2016-07-11 18:25:14
+Encryption key....: 380C 0F4C A077 779A D4D4 93D6 F3FC E22D CDB8 95CB created ....: 2016-07-11 18:25:14
+Authentication key: 8D02 04DF 42FC 2133 8356 DDFB EB09 2344 9913 9572 created ....: 2016-07-11 18:25:14
+General key info..: [none]
+
+$ ssh-add -L
+ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCSMiUCfHXItvZuUP3xO7hjIBukVl9cILSjSapM8WNS8IdyJJrZE00fy30jUwxCeCzSGDMi3WwLlAby99jVyTRgdxb5qHPWaT0k7MmkWLs9vydpZBLLeeyS3KQBrGcwrIA0h0p7A1kCXesiVL6cQCsGMxfQf1YWFBaL5VamXxpfSmz6ia8BEtQJjhJ2NpsyAuAJEs2dPdc5xn/ZRbY+pHV8ruoK0JJdH3c/us6rbrNHKfGnkE5anbKNoMposie3ADjc5ElEFjfAmJ7WxFGvRHA5P51B3jcjSYx4YQvUGq3sW3AhBjfD9VuBIjXDR6B6PKNZSAesWjatTA4fJY1mcw1x cardno:000604550276
+```
+
+To forward your gpg-agent and ssh-agent to remote machines, I add the following lines to my .ssh/config:
+```properties
+RemoteForward /home/harald/.gnupg/S.gpg-agent /home/harald/.gnupg/S.gpg-agent
+RemoteForward /home/harald/.gnupg/S.gpg-agent3 /home/harald/.gnupg/S.gpg-agent3
+StreamLocalBindUnlink yes
+ForwardAgent yes
+```
+
+OpenSSH has a [bug](https://bugzilla.mindrot.org/show_bug.cgi?id=2601), so that `StreamLocalBindUnlink yes` does not
+work in the client configuration and thus, you have to add that option to the remote server `/etc/ssh/sshd_config`
--- a/content/2016/07/_index.md
+++ b/content/2016/07/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2016/11/15/_index.md
+++ b/content/2016/11/15/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2016/11/15/dracut-and-cve-2016-4484-cryptsetup-initrd-root-shell.md
+++ b/content/2016/11/15/dracut-and-cve-2016-4484-cryptsetup-initrd-root-shell.md
@ -0,0 +1,11 @@
+++
+title = "dracut and CVE-2016-4484: Cryptsetup Initrd root Shell"
+date = 2016-11-15T16:42:23+00:00
+++
+People who want to secure their Fedora/RHEL system have to:
+* add a BIOS password
+* add a grub password
+* add "rd.shell=0" to the kernel command line
+
+Anaconda does add "rd.shell=0" to the kernel command line automatically, if you setup the bootloader with a password.
+<!-- more -->
--- a/content/2016/11/_index.md
+++ b/content/2016/11/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2016/12/09/_index.md
+++ b/content/2016/12/09/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2016/12/09/rust-echo-server.md
+++ b/content/2016/12/09/rust-echo-server.md
@ -0,0 +1,11 @@
+++
+title = "Rust Echo Server"
+date = 2016-12-09T14:23:35+00:00
+++
+On modern CPUs, rust seems to perform very nicely with the thread context switches, 
+at least when benchmarking an [echo server](https://github.com/haraldh/rust_echo_server). 
+For that I also wrote an [echo server benchmark client](https://github.com/haraldh/rust_echo_bench). 
+<!-- more -->
+
+The [README.md](https://github.com/haraldh/rust_echo_server/blob/master/README.md) of the server also 
+contains some benchmark numbers.
--- a/content/2016/12/_index.md
+++ b/content/2016/12/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2016/_index.md
+++ b/content/2016/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2017/12/18/_index.md
+++ b/content/2017/12/18/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2017/12/18/varlink.md
+++ b/content/2017/12/18/varlink.md
@ -0,0 +1,155 @@
+++
+title = "Varlink"
+date = 2017-12-18T12:22:38+00:00
+++
+
+For a long time we tried to solve the early boot IPC problem. IPC problem you ask? Well, in the early boot phase we
+cannot talk D-BUS, because the daemon is not running yet, but to bring up the system, so that the D-BUS daemon can run
+(mount stuff, load modules, start other services), we need some kind of IPC. Therefore all the early boot daemons have a
+fallback IPC via unix domain sockets with its own homegrown protocol.
+
+<!-- more -->
+
+### K-DBUS ###
+
+Moving the D-BUS daemon in the kernel was our first approach, but with all the functionality the D-BUS daemon
+has (signal broadcasting, etc.), there was no clean solution possible, which satisfied all kernel devs.
+
+### BUS1 ###
+
+BUS1 was written, but turned out overly complex and was just a transport without a protocol.
+
+### Varlink
+
+While BUS1 was developed as a transport, our team was looking for a protocol and tried simplifying the D-BUS protocol.
+After a lot of iterations not even the variant data protocol was left. Instead Kay Sievers and Lars Karlitski came up
+with a super simple JSON based IPC protocol, which only needs a point-to-point connection, so BUS1 was not even needed.
+
+## KISS
+
+The [varlink](http://varlink.org/) protocol is so simple, that language bindings can be implemented easily and using
+varlink does not result into spending more time coding for IPC than for the actual problem.
+Bindings for
+[C](https://github.com/varlink/libvarlink),
+[Javascript](https://github.com/varlink/org.varlink.http),
+[Go](https://github.com/varlink/org.varlink.http),
+[Java](https://dentrassi.de/2017/12/17/varlink-for-java-what-wonderful-world-it-could-be/),
+[Python](https://github.com/varlink/python-varlink) 
+and [Rust](https://github.com/varlink/rust-varlink) were quickly implemented (some still only as a proof of concept). 
+[A service for resolving interface](https://github.com/varlink/org.varlink.resolver) names into connection 
+URLs and starting the executable has been written, which resembles some of the D-BUS functionality of resolving 
+and activating services.
+
+## APIs
+
+The most important feature of varlink though, is in the interface definition files. They are human readable and can 
+be even discussed amongst people, which are not developing the implementation. They enable a "checks and balance" 
+system for product management, customers, quality engineering and software developers. Interface stability and 
+backwards compatibility can be enforced easily.
+To quote the varlink [Ideals page](https://github.com/varlink/documentation/wiki/Ideals):
+
+> ### Simplicity ###
+>
+> Varlink aims to be as simple as possible. It is not specifically optimized for anything else but ease-of-use and maintainability.
+>
+> ### [](https://github.com/varlink/documentation/wiki/Ideals#discoverability)Discoverability ###
+>
+> Varlink services describe themselves; with a machine-readable interface definition, and human-readable documentation.
+>
+> ### [](https://github.com/varlink/documentation/wiki/Ideals#remotability)Remotability ###
+>
+> It should be easy to forward, proxy, redirect varlink interfaces over any connection-oriented transport. Varlink should be free of any side-effects of local APIs. All interactions need to be simple messages on a network, not carrying things like file descriptors or references to locally stored files.
+>
+> ### [](https://github.com/varlink/documentation/wiki/Ideals#focus)Focus ###
+>
+> Varlink is the protocol and definition of interfaces, but it does not define or provide any significant functionality itself.
+>
+> ### [](https://github.com/varlink/documentation/wiki/Ideals#errors)Errors ###
+>
+> Varlink errors should carry enough information to be consumed by machines and automated rules.
+>
+> ### [](https://github.com/varlink/documentation/wiki/Ideals#testing)Testing ###
+>
+> Making it easy to run automated tests against varlink interfaces should be considered a necessity when designing interfaces.
+
+Right now the API to a Linux system consists of:
+* kernel: ioctls, syscalls, procfs, sysfs
+* CLI: options, stdout output to be parsed
+* D-BUS, Protobuf, various other IPC, homegrown IPC protocols, …
+
+All these can be replaced by varlink interfaces (yes, even the [kernel interfaces](https://github.com/varlink/linux-varlink)).
+Of course varlink is the [15th xkcd standard](https://xkcd.com/927/) here :-P If the adoption of varlink takes off,
+then the collection of interfaces could form a common Linux System API.
+
+These interface definitions can be inspected even at runtime via a common interface named `org.varlink.service`,
+which every service provides. With this mechanism it is very easy for interpreter languanges
+to create bindings at runtime, as we will see in the next chapter.
+
+## Varlink for Python
+
+Ready for some example on how to use varlink with python? First we need some packages to install on Fedora: 
+```console
+$ sudo dnf copr enable "@varlink/varlink"
+$ sudo dnf install fedora-varlink
+$ sudo setenforce 0 # needed until systemd is able to create sockets in /run
+$ sudo systemctl enable --now org.varlink.resolver.socket
+$ varlink help
+```
+
+In this example, we will call an interface called `com.redhat.system.accounts` which has the following varlink interface: 
+```varlink
+interface com.redhat.accounts
+
+type Account (
+    name: string,
+    uid: int,
+    gid: int,
+    full_name: string,
+    home: string,
+    shell: string
+)
+
+# Retrieve a list of account information for all known accounts
+method GetAll() -> (accounts: []Account)
+# Retrieve the account information for a specific user ID
+method GetByUid(uid: int) -> (account: Account)
+# Retrieve the account information
+method GetByName(name: string) -> (account: Account)
+# Add new account
+method Add(account: Account) -> (account: Account)
+
+error NotFound ()
+error CreationFailed (field: string)
+```
+ 
+From reading the interface definition, the API should be understandable,
+even for people, who have never seen a varlink interface file.
+
+Now, let's call the service from some python code:
+```python
+from varlink import Client
+client = Client(resolve_interface='com.redhat.accounts')
+accounts = client.open('com.redhat.accounts', namespaced=True)
+ret = accounts.GetByName("root")
+print(ret)
+```
+
+will output:
+
+```python
+namespace(account=namespace(full_name='root', gid=0, home='/root', name='root', shell='/bin/bash', uid=0))
+```
+
+and
+
+```python
+>> print(ret.account.full_name, ret.account.uid, ret.account.shell)
+```
+
+will output:
+```
+root 0 /bin/bash
+```
+
+That's it! And the varlink python module is also very small.
+Stay tuned for more and go read [Jens Reinmann's Java Varlink blog post](https://dentrassi.de/2017/12/17/varlink-for-java-what-wonderful-world-it-could-be/).
--- a/content/2017/12/_index.md
+++ b/content/2017/12/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2017/_index.md
+++ b/content/2017/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2018/02/22/_index.md
+++ b/content/2018/02/22/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2018/02/22/varlink-and-the-elvish-shell.md
+++ b/content/2018/02/22/varlink-and-the-elvish-shell.md
@ -0,0 +1,16 @@
+++
+title = "varlink and the elvish shell"
+date = 2018-02-22T09:53:37+00:00
+++
+I recently discovered [Elvish](https://elvish.io/), which is a shell perfectly 
+suited to process structured data. In my case it is perfect to be used with 
+[varlink](http://varlink.org). Too bad elvish has no numeric type and 
+can't feed varlink with int and float, because to\-json converts them to strings. 
+
+<!-- more -->
+
+<img src=https://harald.hoyer.xyz/wp-content/uploads/sites/2/2018/02/Screenshot-from-2018-02-22-11-07-04.png>
+
+To see what I mean, watch this video:
+ 
+ [![video preview](/img/elvis-varlink-screencast.png)](https://asciinema.org/a/bB3OatlJltV3tTdSRpsrQELxQ).
--- a/content/2018/02/22/varlink-for-dnf-a-showcase.md
+++ b/content/2018/02/22/varlink-for-dnf-a-showcase.md
@ -0,0 +1,6 @@
+++
+title = "varlink for dnf - a Showcase"
+date = 2018-02-22T07:09:03+00:00
+++
+On the [varlink wiki page](https://github.com/varlink/documentation/wiki/Adding-varlink-to-DNF) I showcase how to add varlink to a python project. In this case, I chose DNF, the rpm package manager of Fedora.
+<!-- more -->
--- a/content/2018/02/_index.md
+++ b/content/2018/02/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2018/_index.md
+++ b/content/2018/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2019/02/07/_index.md
+++ b/content/2019/02/07/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2019/02/07/bat-understands-varlink-now.md
+++ b/content/2019/02/07/bat-understands-varlink-now.md
@ -0,0 +1,84 @@
+++
+title = "Bat understands varlink now"
+date = 2019-02-07T07:04:47+00:00
+++
+[Bat](https://github.com/sharkdp/bat) is a *cat(1)* clone with syntax highlighting and Git integration.
+
+My pull request for varlink syntax coloring was accepted today :\-)
+
+<!-- more -->
+
+So, to display:
+
+```varlink
+# The Varlink Service Interface is provided by every varlink service. It
+# describes the service and the interfaces it implements.
+interface org.varlink.service
+
+# Get a list of all the interfaces a service provides and information
+# about the implementation.
+method GetInfo() -> (
+  vendor: string,
+  product: string,
+  version: string,
+  url: string,
+  interfaces: []string
+)
+
+# Get the description of an interface that is implemented by this service.
+method GetInterfaceDescription(interface: string) -> (description: string)
+
+# The requested interface was not found.
+error InterfaceNotFound (interface: string)
+
+# The requested method was not found
+error MethodNotFound (method: string)
+
+# The interface defines the requested method, but the service does not
+# implement it.
+error MethodNotImplemented (method: string)
+
+# One of the passed parameters is invalid.
+error InvalidParameter (parameter: string)
+```
+
+it will look like this:
+
+<pre style="background-color: black;color: white"><b>$</b> bat org.varlink.service.varlink
+<font color="#444444">───────┬───────────────────────────────────────────────────────────────────────────────</font>
+       <font color="#444444">│ </font>File: <b>org.varlink.service.varlink</b>
+<font color="#444444">───────┼───────────────────────────────────────────────────────────────────────────────</font>
+<font color="#444444">   1</font>   <font color="#444444">│</font> <font color="#75715E"># The Varlink Service Interface is provided by every varlink service. It</font>
+<font color="#444444">   2</font>   <font color="#444444">│</font> <font color="#75715E"># describes the service and the interfaces it implements.</font>
+<font color="#444444">   3</font>   <font color="#444444">│</font> <font color="#66D9EF">interface</font><font color="#F8F8F2"> </font><font color="#A6E22E">org.varlink.service</font>
+<font color="#444444">   4</font>   <font color="#444444">│</font> 
+<font color="#444444">   5</font>   <font color="#444444">│</font> <font color="#75715E"># Get a list of all the interfaces a service provides and information</font>
+<font color="#444444">   6</font>   <font color="#444444">│</font> <font color="#75715E"># about the implementation.</font>
+<font color="#444444">   7</font>   <font color="#444444">│</font> <font color="#66D9EF">method</font><font color="#F8F8F2"> </font><font color="#A6E22E">GetInfo</font><font color="#F8F8F2">() </font><font color="#F92672">-&gt; </font><font color="#F8F8F2">(</font>
+<font color="#444444">   8</font>   <font color="#444444">│</font> <font color="#F8F8F2">  </font><font color="#FD971F">vendor</font><font color="#F8F8F2">: </font><font color="#66D9EF">string</font><font color="#F8F8F2">,</font>
+<font color="#444444">   9</font>   <font color="#444444">│</font> <font color="#F8F8F2">  </font><font color="#FD971F">product</font><font color="#F8F8F2">: </font><font color="#66D9EF">string</font><font color="#F8F8F2">,</font>
+<font color="#444444">  10</font>   <font color="#444444">│</font> <font color="#F8F8F2">  </font><font color="#FD971F">version</font><font color="#F8F8F2">: </font><font color="#66D9EF">string</font><font color="#F8F8F2">,</font>
+<font color="#444444">  11</font>   <font color="#444444">│</font> <font color="#F8F8F2">  </font><font color="#FD971F">url</font><font color="#F8F8F2">: </font><font color="#66D9EF">string</font><font color="#F8F8F2">,</font>
+<font color="#444444">  12</font>   <font color="#444444">│</font> <font color="#F8F8F2">  </font><font color="#FD971F">interfaces</font><font color="#F8F8F2">: </font><font color="#F92672">[]</font><font color="#66D9EF">string</font>
+<font color="#444444">  13</font>   <font color="#444444">│</font> <font color="#F8F8F2">)</font>
+<font color="#444444">  14</font>   <font color="#444444">│</font> 
+<font color="#444444">  15</font>   <font color="#444444">│</font> <font color="#75715E"># Get the description of an interface that is implemented by this service.</font>
+<font color="#444444">  16</font>   <font color="#444444">│</font> <font color="#66D9EF">method</font><font color="#F8F8F2"> </font><font color="#A6E22E">GetInterfaceDescription</font><font color="#F8F8F2">(</font><font color="#FD971F">interface</font><font color="#F8F8F2">: </font><font color="#66D9EF">string</font><font color="#F8F8F2">) </font><font color="#F92672">-&gt; </font><font color="#F8F8F2">(</font><font color="#FD971F">description</font><font color="#F8F8F2">: </font><font color="#66D9EF">string</font><font color="#F8F8F2">)</font>
+<font color="#444444">  17</font>   <font color="#444444">│</font> 
+<font color="#444444">  18</font>   <font color="#444444">│</font> <font color="#75715E"># The requested interface was not found.</font>
+<font color="#444444">  19</font>   <font color="#444444">│</font> <font color="#66D9EF">error</font><font color="#F8F8F2"> </font><font color="#A6E22E">InterfaceNotFound</font><font color="#F8F8F2"> (</font><font color="#FD971F">interface</font><font color="#F8F8F2">: </font><font color="#66D9EF">string</font><font color="#F8F8F2">)</font>
+<font color="#444444">  20</font>   <font color="#444444">│</font> 
+<font color="#444444">  21</font>   <font color="#444444">│</font> <font color="#75715E"># The requested method was not found</font>
+<font color="#444444">  22</font>   <font color="#444444">│</font> <font color="#66D9EF">error</font><font color="#F8F8F2"> </font><font color="#A6E22E">MethodNotFound</font><font color="#F8F8F2"> (</font><font color="#FD971F">method</font><font color="#F8F8F2">: </font><font color="#66D9EF">string</font><font color="#F8F8F2">)</font>
+<font color="#444444">  23</font>   <font color="#444444">│</font> 
+<font color="#444444">  24</font>   <font color="#444444">│</font> <font color="#75715E"># The interface defines the requested method, but the service does not</font>
+<font color="#444444">  25</font>   <font color="#444444">│</font> <font color="#75715E"># implement it.</font>
+<font color="#444444">  26</font>   <font color="#444444">│</font> <font color="#66D9EF">error</font><font color="#F8F8F2"> </font><font color="#A6E22E">MethodNotImplemented</font><font color="#F8F8F2"> (</font><font color="#FD971F">method</font><font color="#F8F8F2">: </font><font color="#66D9EF">string</font><font color="#F8F8F2">)</font>
+<font color="#444444">  27</font>   <font color="#444444">│</font> 
+<font color="#444444">  28</font>   <font color="#444444">│</font> <font color="#75715E"># One of the passed parameters is invalid.</font>
+<font color="#444444">  29</font>   <font color="#444444">│</font> <font color="#66D9EF">error</font><font color="#F8F8F2"> </font><font color="#A6E22E">InvalidParameter</font><font color="#F8F8F2"> (</font><font color="#FD971F">parameter</font><font color="#F8F8F2">: </font><font color="#66D9EF">string</font><font color="#F8F8F2">)</font>
+<font color="#444444">───────┴───────────────────────────────────────────────────────────────────────────────</font>
+</pre>
+
+
+
--- a/content/2019/02/_index.md
+++ b/content/2019/02/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/2019/_index.md
+++ b/content/2019/_index.md
@ -0,0 +1,5 @@
+++
+transparent = true
+sort_by = "date"
+paginate_by = 5
+++
--- a/content/_index.md
+++ b/content/_index.md
@ -0,0 +1,4 @@
+++
+paginate_by = 5
+sort_by = "date"
+++
--- a/content/pages/_index.md
+++ b/content/pages/_index.md
@ -0,0 +1,3 @@
+++
+render = false
+++
--- a/content/pages/impressum.md
+++ b/content/pages/impressum.md
@ -0,0 +1,23 @@
+++
+title = "Impressum"
+path = "impressum"
+date = 2000-01-01
+template = "impressum.html"
+++
+
+# Impressum
+
+Harald Hoyer
+
+Gerda-Penzel-Str. 13
+85591 Vaterstetten
+
+Email:webmaster@harald.hoyer.xyz
+
+GPG key: current [0x4BC0896FB5693595](https://harald.hoyer.xyz/files/gpg-key.txt) as seen on the key servers and [people.redhat.com](https://people.redhat.com/harald/gpg-pub-7F3D64824AC0B6B8009E50504BC0896FB5693595.asc)
+
+
+Keybase: [https://keybase.io/haraldhoyer/](https://keybase.io/haraldhoyer/)
+
+
+old GPG key (not compromised): C5575542 as seen on the key servers
--- a/static/img/about-bg.jpg
+++ b/static/img/about-bg.jpg
--- a/static/img/contact-bg.jpg
+++ b/static/img/contact-bg.jpg
--- a/static/img/elvis-varlink-screencast.png
+++ b/static/img/elvis-varlink-screencast.png
--- a/static/img/home-bg.jpg
+++ b/static/img/home-bg.jpg
--- a/static/img/post-bg.jpg
+++ b/static/img/post-bg.jpg
--- a/syntaxes/Sublime-console/commands-builtin-shell-bash.sublime-syntax
+++ b/syntaxes/Sublime-console/commands-builtin-shell-bash.sublime-syntax
--- a/syntaxes/Sublime-console/console.sublime-syntax
+++ b/syntaxes/Sublime-console/console.sublime-syntax
--- a/syntaxes/Sublime-varlink/varlink.sublime-syntax
+++ b/syntaxes/Sublime-varlink/varlink.sublime-syntax
@ -0,0 +1,95 @@
+%YAML 1.2
+---
+name: varlink
+file_extensions:
+  - varlink
+scope: source.varlink
+
+variables:
+  interface_name: '([a-z](\-*[a-z0-9])*(\.[a-z0-9](\-*[a-z0-9])*)+)'
+  identifier: '([A-Z][a-zA-Z0-9_]*)'
+  field_name: '[A-Za-z]([_]?[A-Za-z0-9])*'
+
+contexts:
+  main:
+    - include: statements
+
+  statements:
+    - include: comments
+
+    - match: '(interface)\s+(\b{{interface_name}}\b)'
+      scope: meta.type.declaration.varlink
+      captures:
+        1: storage.type.interface.varlink
+        2: entity.name.interface.varlink
+
+    - match: '(method)\s+(\b{{identifier}}\b)\s*(?=[(])'
+      scope: meta.method.declaration.varlink
+      captures:
+        1: storage.type.method.varlink
+        2: entity.name.method.varlink
+      push: [ method-return, block ]
+
+    - match: '(type)\s+(\b{{identifier}}\b)\s*(?=[(])'
+      scope: meta.type.declaration.varlink
+      captures:
+        1: storage.type.type.varlink
+        2: entity.name.type.varlink
+      push: block
+
+    - match: '(error)\s+(\b{{identifier}}\b)\s*(?=[(])'
+      scope: meta.error.declaration.varlink
+      captures:
+        1: storage.type.error.varlink
+        2: entity.name.error.varlink
+      push: block
+
+  method-return:
+    - match: '(->)\s*(?=[(])'
+      scope: keyword.operator.varlink
+      set: block
+
+  block:
+    - include: comments
+    - match: '\)'
+      scope: punctuation.section.group.end.varlink
+      pop: true
+    - match: '\('
+      scope: punctuation.section.group.begin.varlink
+      push: block-inner
+
+  block-inner:
+    - include: comments
+    - match: '(?=\))'
+      pop: true
+    - match: '\b{{field_name}}\b'
+      scope: variable.parameter.varlink
+    - match: ','
+      scope: punctuation.separator.varlink
+    - match: ":"
+      scope: punctuation.separator.varlink
+      push: type
+
+  type:
+    - include: comments
+    - match: '(?=\()'
+      push: block
+    - match: '(?=\))'
+      pop: true
+    - match: '(?=,)'
+      pop: true
+    - match: '\b(string|bool|int|float|object)\b'
+      scope: storage.type.varlink
+    - match: '(\[\]|\[string\]|\?)'
+      scope: storage.modifier.varlink
+    - match: '\b{{identifier}}\b'
+      scope: entity.name.type.varlink
+
+  comments:
+    - match: "#"
+      scope: punctuation.definition.comment.varlink
+      push:
+        - meta_scope: comment.line.documentation.varlink
+        - match: $\n?
+          pop: true
+